Fluoroscopy provides near real-time visualization of internal anatomy of a patient, with the ability to monitor dynamic processes, including tracking the relative motion of various types of features such as probes or other devices, fluids, and structures. Fluoroscopy is used, for example to help in diagnosis and to position the patient for subsequent image recording or to position and manipulate various types of devices for interventional procedures.
The block diagram of FIG. 1 shows components in the imaging path of a conventional fluoroscopy system 10 for obtaining images of a patient 14 or other subject. Radiation from an x-ray source 20 that typically uses a collimator 22 and filtration 24 is directed through a patient 14 to an image intensifier 30. Generally a grid 32 is provided. A camera 40 then captures successive video frames from the x-ray exposure and generates images that are displayed on a display monitor 44.
To reduce the exposure of the patient to ionizing radiation, conventional fluoroscopy practices use the collimator 22 to limit the size of the exposure field as much as possible. Adjustments to collimator 22 are made using an initial “scout image” to ascertain how well the radiation beam is centered and how much adjustment of the collimators can be allowed in order to direct radiation to the region of interest (ROI) for a particular patient 14. The practitioner views the scout image and makes adjustments accordingly, then begins the active imaging sequence for fluoroscopy. This procedure is time-consuming and approximate, sometimes requiring repetition of the adjustment to correct for error. Moreover, movement of the patient or ongoing progress of a contrast agent or probe or other device can cause the ROI to shift, requiring that the imaging session be repeatedly paused in order to allow for collimator readjustment.
As digital radiography (DR) imaging receivers steadily improve in image quality and acquisition speed, it is anticipated that these devices can be increasingly employed not only for conventional radiography imaging, but also for fluoroscopy applications, effectively eliminating the need for the dedicated image intensifier hardware used with conventional fluoroscopy systems such as that shown in FIG. 1.